Cu(II) hexacyanoferrate (III) modified carbon paste electrode; Application for electrocatalytic detection of nitrite

Copper hexacyanoferrate (CuHCF) film-modified carbon paste electrode (CPE) has been prepared from various electrolytic aqueous solutions using consecutive cyclic voltammetry. The cyclic voltammograms showed the direct deposition of CuHCF films from the mixing of Cu2+ and Fe(CN)(6)(3-) ions and each time with one of the six cations: H+, Na+, K+, NH4+, Mg2+, and Al3+. The CuHCF film showed a single redox couple that exhibited a cation effect (Na+, K+, Mg2+, and NH4+) and anion effect (Cl-, NO3-, SO42-, ClO4- and BrO3-) in the cyclic voltammograms. Voltammetric studies have indicated that in presence of nitrite, the cathodic peak current of CuHCF increases, followed by a decrease in the corresponding anodic current. This indicated that nitrite was reduced by the redox mediator immobilized oil the electrode surface via an electrocatalytic mechanism. The process of reduction and its kinetics were investigated by using cyclic voltammetry, differential pulse voltammetry. chronoamperometry and chronocoulometry techniques. The electrocatalytic ability about 800 mV can be seen. The rate constant of the catalytic reduction of nitrite was found to be 7.9 x 10(5) cm(3) mol(1) s(-1). Linearity range obtained was 5 x 10(-5) - 8.4 x 10(-3) by cyclic voltammetry and 8 x 10(-6) - 1.3 x 10(-3) and 4 x 10(-3) - 2 x 10(-2) by differential pulse voltammetry.